Fabrication and Characterization of Ultrathin PBCO/YBCO/PBCO Constrictions for Hot Electron Bolometer THz Mixing Application

Abstract

Superconducting Hot Electron Bolometer (HEB) mixers are a competitive alternative to conventional mixer technologies in the terahertz range because of their ultrawide bandwidth, high conversion gain, and low intrinsic noise level, even at 77 K. A technological process to realize HEBs based on high-Tc YBa 2 Cu 3 O 7 (YBCO) materials is described. Ultrathin 12 to 40 nm layers were sputtered on MgO (100) substrates, sub-micrometer constrictions (0 5 m 0 5 m) were etched on these and log-periodic gold antennas were then integrated. Good superconducting properties were measured after the whole process. Electrical transport characteristics of the device are discussed, ageing effects are considered and regular bolometric THz response results are given.Index Terms-Electrical transport, hot-electron bolometer, submicron structures, terahertz wave detection, YBCO ultrathin film.

Superconducting hot-electron bolometer: from the discovery of hot-electron phenomena to practical applications

“…In 1987, Gershenzon et al [158,159] were the first to propose using YBCO films for the implementation of an HEB. The proposed film had a thickness of ∼1 mm and T c of ∼94 K. Since then, data on fabrication and measurements of YBCO-based HEB devices have been reported by numerous groups [160][161][162][163][164][165][166]. Even though YBCO HEB detectors are not as sensitive as low-T c devices at the moment, they can still compete with semiconductor-based detectors such as Schottky diodes.…”

Terahertz Emitters, Detectors and Sensors: Current Status and Future Prospects

“…The discovery of high temperature superconductors has helped in increasing the operating temperature of the HEBs to liquid nitrogen temperatures. For example, an ultrathin PBCO/YBCO/PBCO HEB [Peroz et al, 2007] constructed by ultra-thin (10 nm thick) superconducting micro-bridge coupled with a planar antenna was demonstrated. However, the limitation on mixing operation of HEB is observed causing by aging of thinner layer and nano bridge structure.…”